A LOW POWER, LOW NOISE CHOPPER INSTRUMENTATION AMPLIFIER USING BODY CONTROL DC-SERVO LOOP AND LOW INPUT CAPACITANCE

Abstract

This paper presents a proposed low power, low noise capacitively-coupled
chopper instrumentation amplifier (CCIA) using body control DC servo loop and
low input capacitance applied for biomedical recording. A DC servo loop using
body control (DSL-BC) is proposed to reduce the electrode offset and its noise
contribution. A T-bridge capacitance network is employed in the negative
feedback loop to save the chip area. Also, a positive feedback loop (PFL) is
utilized to improve input impedance. The proposed circuit is simulated in a
standard 0.18µm CMOS technology. According to simulated results, the proposed
CCIA achieves the closed-loop gain of 40dB and the input-referred noise of
2.4µVrms over a bandwidth from 1 to 200Hz. The noise efficiency factor NEF of
6.6 is obtained while drawing current consumption of 1µA from a 1V supply. The
active chip area occupies only 0.083mm2.